As a result of stricter regulations for automotive emissions, it was desired to design a testing apparatus and procedure for testing emissions control devices. Historically, actual internal combustion engines have been used for such evaluations. However, the use of a real engine for long term testing can be inconsistent, maintenance intensive, and expensive to operate. In addition, a real engine does not conveniently permit the separate evaluation of individual variables, such as the effects of various constituents of fuel and oil.
U.S. Patent Pub. No. 2003/0079520, entitled “Method and Apparatus for Testing Catalytic Converter Durability” and U.S. Patent Pub. No 2004/0007056 A1, entitled “Method for Testing Catalytic Converter Durability”, both describe an exhaust flow simulation system. The system comprises a fuel-combustive burner with an integrated, computerized control system. The system realistically simulates the flow and composition of exhaust gas from an engine under a variety of load conditions.
A burner-based exhaust gas simulation system generates exhaust at elevated temperatures, as high as 1000 degrees or more. Yet, for testing purposes, the exhaust gas may need to be at a specific temperature or range of temperatures. Thus, for testing purposes, good temperature control is required. In the systems described in the preceding paragraph, a heat exchanger downstream the burner is used for temperature control.